The present invention relates to the field of watchmaking, more particularly to a device for locking the mechanism for rewinding and setting the time of a watch.
Most watches, whether these be of the mechanical or quartz-driven type, necessarily need some mechanism for setting the time. In the case of mechanical watches, this mechanism also allows the input of external work needed for them to operate. This mechanism is actuated by an external button usually placed on one side of the watch and known as the winding button. This button allows access to the other functions offered by the watch, such as setting the date or changing the time zone.
When performing deep dives, the winding button is an area which is sensitive as far as watertightness is concerned, because the external pressure of the water on the casing is high and water may seep in past the winding button seals. What is more, it is possible during the dive that the wrist may strike an object and that the button may be pulled out inadvertently into its time-setting position. This has two serious consequences, one concerning the watertightness, which is reduced in this position, and the other concerning the possibility that the time setting might be altered or that the watch might stop. The latter consequence is particularly dangerous because a change to the time may cause accidents (incorrect calculation of the dive time and length of the decompression stops).
A widely used solution in the field of diving watches is the use of a screw-in winding button, that is to say that before making a dive, the winding button is screwed into the case. In order to allow the winding button to be turned in its function of rewinding the spring barrel, without engaging the screwed part of the winding button in the case, the button incorporates a spring which exerts pressure which holds the two threaded parts apart. To engage the screw thread of the button in the case, it is necessary to press the button against the case. In the screwed-in position, the button butts against the case, where an additional seal is usually fitted in order to provide good watertightness. While this solution guarantees good protection against the two aforementioned problems, it has the disadvantage of requiring an operation prior to diving, without which it is completely ineffective.
Another solution has been developed and uses a special bridge surrounding the winding button, which has a lever which presses the winding button against the case. This solution is found, in particular, on Italian Panarai(copyright) diving watches.
This solution, although it gives good results from a technical standpoint, is bulky and makes the watch slightly wider.
The object of the present invention is to be able to have a compact mechanism that locks the winding button in its position of rest, that is to say in the position for rewinding the spring barrel, and thus prevents the button from being pulled out at an inopportune moment.
The object of the invention is achieved through the use of a winding button with a central internal groove and a lever, the central part of which rests on this groove.
The special shape, known as the H-shape, of the winding button makes it possible to obtain very compact locking which does not exceed the length of the button. The central part of the lever lies across the groove that the small diameter of the H forms. One of the ends of the lever can rotate on a pin and the other end is locked on the other side of the button. Thus, when the lever is in place, it forms a rigid assembly extending from the rotation pin, passes between the two flanges of the button, and ends on the fastener.
Fastening may be achieved in various ways, for example by clipping onto a pin.
The button can be turned by hand by the teeth on the periphery of the two flanges.
The advantage of this solution is its simplicity, its robustness and its elegance. It locks the button in place at all times because it is not possible to leave the lever open, something which is not the case with the screw-in button, for example.